1. Field of the Invention
The present invention relates to a magnetic tape unit for writing information on a magnetic tape or reading the information from the magnetic tape.
2. Description of the Related Art
FIGS. 1A and 1B shows a conventional magnetic tape unit.
Referring to FIGS. 1A and 1B, the conventional magnetic tape unit is provided with a take-up reel 8 for winding a magnetic tape thereon by rotating about a rotation center 12, a threader pin 11 from which a leader block 7 connected to the front end of a magnetic tape 6 housed in a cartridge 5 is suspended, a threader arm 4 for leading the leader block 7 from a tape exit 15 of the cartridge 5 up to an inside 16 of the take-up reel 8 by leading the threader pin 11 from the tape exit 15 of the cartridge 5 up to the rotation center 12 of the take-up reel 8, and a motor 2 for driving the threader arm 4. Moreover, the threader arm 4 is driven by the motor 2 through a driving arm 3.
Reference numeral 13 denotes a rotating shaft of the motor, which also serves as a rotating shaft of the driving arm 3. Reference numeral 14 denotes a rotating shaft of the threader arm 4. Therefore, the motor 2 and driving arm 3 rotate about the rotating shaft 13 and the threader arm 4 rotates about the rotating shaft 14 in accordance with the contact between a pin 17 provided to the driving arm 3 and a groove 18 provided to the threader arm 4.
A rotary encoder (not illustrated) is set to the rotating shaft 14 of the threader arm and position sensors (not illustrated) are set to positions nearly reaching two of the stop positions of the threader arm 4. The two stop positions are the position where the threader arm 4 holds the leader block 7 housed in the cartridge 5 and the position where the threader arm 4 is set to the rotation center 12 of the take-up reel 8. A motor driving circuit (not illustrated) controls the position and speed of the threader pin 11 by controlling the angle and angular speed of the motor on the basis of the rotary encoder and these two position sensors.
In the case of the above magnetic tape unit, the position of the threader arm 4 is indeterminate due to the backlash of each operating portion of a threader mechanism and the center of the threader pin 11 may be shifted from the rotation center 12 of a machine reel after the threader pin 11 set to the threader arm 4 carries the leader block 7 set to the front end of the magnetic tape 6, the leader block 7 is set in the take-up reel 8, and the threading operation is completed. When running the magnetic tape 6 under the above state, a threader mechanism vibrates due to the backlash.
When the position of a threader arm is indeterminate due to the backlash of each operating portion of the threader mechanism, the center of the threader pin 11 set to the threader arm 4 may be shifted from the rotation center 12 of the take-up reel. When running a tape in the above state, the threader pin 11 interferes with the leader block 7 and the threader mechanism may vibrate.
The present invention is made to solve the above problems and its object is to provide a magnetic tape unit capable of preventing a threader pin from shifting from the rotation center of a take-up reel while the magnetic tape unit operates.
According to the present invention, there is provided a magnetic tape unit comprising: a take-up reel for winding a magnetic tape thereon; a threader pin from which a leader block connected to a front end of the magnetic tape housed in a cartridge is suspended; a threader arm to which the threader pin is attached in order to lead the leader block from a tape exit of the cartridge up to an inside of the take-up reel by leading the threader pin from the tape exit of the cartridge up to the rotation center of the take-up reel; and an elastic body for restricting the backlash of the position of the threader arm by an elastic force so that the threader pin present at the rotation center of the take-up reel does not shift from the rotation center.
In the magnetic tape unit, the elastic force may be pressure.
In the magnetic tape unit, the elastic force may be tension.
In the magnetic tape unit, the elastic body may be selected from the group consisting of a rubber block, a compression coil spring, a tensile coil spring, a leaf spring, a torsion coil spring, and a resin block.
The magnetic tape unit may further comprise driving means for driving the threader arm.
In the magnetic tape unit, the threader arm may be driven by the motor through a driving arm.